Physical Foundations

Physical Foundations

Penetration Depths

Penetration depth refers to the distance over which one substance or object can penetrate another substance or object. Depending on the specific context and the materials involved, it can be measured in various units such as meters, centimeters, or millimeters.

Physical Basis of Microwave Heating in Molecules

Microwave heating, a form of dielectric heating, is the process of generating heat in materials with low electrical conductivity using a high-frequency electric field. To be suitable for microwaves, the molecular structure of a material must be asymmetric, such as a water molecule. The molecules of these compounds form electric dipoles that try to point in the direction of the electric field. This orientation polarisation results in energy production. For more details on the complementary mechanism of space charge polarisation, see the section “Energy conversion in the molecule”.

Energy Conversion in Molecules

Dipole molecules can oscillate in response to pole shifts in the high-frequency field due to the influence of an alternating field. The high-frequency energy is created by the friction between the molecules and is first absorbed before being converted into heat energy. Materials with a symmetrical molecular structure, such as benzene, cannot be heated in a high-frequency field because they lack fundamental dipole properties. An alternating electric field can affect freely moving ions in addition to dipole molecules. Resistive heating results from the collision of these flowing unbounded ions. High-frequency energy is once again absorbed as a result of these collisions and their subsequent conversion into thermal energy. Glass, ceramics, salt solutions, electrolytes, and other materials are an exception at high temperatures. When the frequency is lowered, a significant amount of heat is generated by these materials.